Automatic telephone system.



. c. L. GOODRUM. Aurommc TELEPHONE svsnzm. APPLICATION FILED MAY 4;I901. Patented Nov. 20, 1917.

8 SHEETSSHEET l- C. L. GOODRUM. AUTOMATIC IELEPHONE SYSTEM. APPLICATIONFILED MAY 4. 1907.

Patented Nov. 20, 1917.

8 SHEETS-SHEET 2.

Qvwentoz Wifnwou C. L. GOODRUM. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED MAY 4. I901- 1,24:7,395. V Patented Nov. 20, 1917.

8 SHEETS-SHEET 3- warmma W aka/0% C. L. GOODRUM. AUTOMATIC TELEPHONESYSTEM.

APPLICATION FILED MAYMIBO]. 1 247,395. Patented Nov. 20, 1917.

GZJMK I lvil'ueoaeo Q u v C. L. GOODRUM. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED MAY 4.1907- 1,247,395.

Patented Nov, 20, 1917.

B SHEETSSHEET 5.

N I Jwumtoz C. L. GOODRUM. AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILEDMAY 4, 1901.

Patented Nov; 20, 1917.

8 SHEETS SHEET 6.

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. WI hwaoeo c. L. eoonaum; AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED IAY 4, I907. 1,247,395. I

Patented Nov. 20,1917. I

3 SHEETS-SHEET I.

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slmmnfoz W fly/MA m CHARLES L. eoonnou,

OF ROCHESTER, NEW YORK, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO WESTERNELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

Specification 0! Letters Patent.

AUTOMATIC TELEPHONE SYSTEM.

Patented Nov. 20, 1917.

Application filed May 4, 1907. Serial No. 371,843.

To all whom it may concern:

Be-it known that 1, CHARLES L. GOODRUM, of Rochester, in the county ofMonroe and State of New York, have invented certain new andusefiilImprovements in Automatic Telephone Systems; and I do hereby declare thefollowing to be a full, clear, and exact description of the same,reference being had to the accompanying drawings, forming a part of thespecification, and to the reference-numerals marked thereon.

My present invention relates to automatic telephone systems, and it hasfor its primary object to provide an improved system in which thetalking and signaling operations between different subscribers stations,and the apparatus for connectin difi'erent telephone lines, at thecentral 0 ice or exchange, may all be effected over a full metalliccircuit comprising but two wires without grounded connections.

Another object of the invention is to provide means for connectingdifferent telephone lines at the central ofiice or exchange comprisinggenerally a finder switch and an associate connectorswitch, both servinga plurality of lines, the former operating automatically to select aline on which a call originates and extend it to the connector switchwhich latter is responsive to'impulses of current on the calling lineand serves to connect it to a particular outgoing line on which it isdesired to call a subscriber, the signaling of said called subscriberbeing accomplished automatically.

In addition to the above described attainments of the invention it alsocomprehends the employment of two or more finder switches, the movableelements of which travel in opposite directions, or move in the samedirection to cocperate'with equivalent setsof line or instrument circuitterminals, arranged in reverse positions in the banks of contacts on thetwo switches, whereby one of them will pick up the incoming line inadvance of the other. The arrangement of these parts of the apparatushas this additional function; that should the first switch fail to makethe connection, the line will be subsequently picked *up by the secondfinder switch, when its movable elements engage its respective terminalsof said line.

The arrangement of the parts of the apparatus embodying this inventionpermits another object to be obtained; namely; the location of anincandescent lamp at each subscribers instrument which is lighted bycurrent in the instrument circuit supplied from the central otfice orexchange, when said circuit is closed. The lighting of this lamp as soonas a subscriber removes his receiver,

illuminates the dial of the impulse transmitter and facilitates thesubscriberslabor in sending in a call.

To these and other ends the invention consists in certain improvementsand combinations of parts all as will be hereinafter fully described,the novel. features being pointed out in the claims at the end of thespecification.

In the drawings:

Figures 1 and 2 are illustrating generically the line connection as itis effected between two instrument circuits by means of the finder andconnector switches, the operating mechanism of the switches beingomitted, the first view showing the positions of the switches inconnecting instrument A with instrument B and the second illustratingthe reverse connection.

Fig. 3 is a plan view illustrating a type of switch .which may beemployed as finder and connector switches for operation with thissystem.

Figs. 4 and 5 are detail sectional views thereof taken on the lines P-4:" and 5"-5 respectively.

.Fig. 6 is a diagrammatic view illustrating a finder switch inconjunction with an, in

diagrammatic views strument circuit, including that part of the switchcontrolling mechanism which automatically extends said circuit to theconnector switch, and p Fig. 7 is a similar view of the connector switchshowing the controlling mechanism by means of which the switch connectsan incoming line or circuit, on which a call is originated, to anotheroutgoing line.

Fig. 8 is an enlarged diagrammatic detail view of the devices foroperating the con- ,description,

hector switch illustrating the operation of the mechanism for setting upa connection and subsequently restoring the switch to its normalposition.

Fig. 9 is a diagrammatic illustration of the apparatus associated withthat shown in Figs. 7 and 8 for automatically operating thecallingdevices on the various outgoing lines or c1rcuits intermittentlywhich is arrested when the called subscriber answers his signal.

Fig. 10 is a diagrammatic view showing duphcate arrangement of theassocated finder and connector switches shown in Figs. 6 and 7.

Similar reference numerals in the several figures indicate similarparts.

In a telephone exchange. system embodyin my invention the connectionsbetween difierent telephone lines are automatically set up or-efl'ectedby apparatus arranged at the central office or exchange, and thetelephone lines or circuits are divided into two classes comprising,first, incoming lines or those on which calls are ori inated, by subscribers who desire toesta cation with other parties, and, secondly,outgoing lines over which the calls are'despatched to signal saidparties. Each line may, at different times, be of either class and itwill therefore be understood when these lines are referred to in thefollowing that an incoming line or circuit is one leading from asubscribers telephone or station over which impulses of current are sentto connect said line to an outgoing line and that the latter is theoneon which the signaling devices are actuated when the connection hasbeen set up or completed between the telephone instruments of the callinand the called subscribers.

n the system embodying the present invention it is possible to connectthrough the central oflice or exchange apparatus a given line with anyother line and to this end all the lines lead to terminals on a finderswitch, or a pluralit of such switches, and to simi lar termina s on anassociate connector switch or switches. The finder switch -performs thefunction of selecting an incoming line on which a call has beenoriginated, and the connector switch performs a similar function inselecting the outgoing line leadin to a particular telephone instrumentor sufiscribers station, with which the calling subscriber desires tocommunicate. The movable elements or wipers of the finder and connectorswitches are connected, or tied together, so that when the functions ofeach have been performed, the talking circuit, from the incoming to theoutgoing line, is extended throu h them and ma be retained until one oft e twocommumcating subscribers desires to effect the discon- 66 nectionof said lines.

lish communir In Figs, ,1 and 2 the above described connections areshown diagrammatically, two separate instruments being shown in each,and indicated generally'by A and B, with a singlefinder switch F and asingle connector switchC. In Fig. 1, the movable elements or wipers ofthe two switches are shown in position to illustrate the connectionestablished from'instrument A to instrument B when the circuit of thefirst mentioned instrument is the incoming line on which a call isoriginated, and In Fig. 2 these parts of the switches are shown in theposition which they occupy when instrument B is the one on which a callwas initiated. I

The telephone instruments may be of the usual or any preferredconstruction comprising generally a transmitter 1, a receiver 2, and thesignaling devices or bells 3, all of which are arranged in the circuitof the line wires AA of instrument A, and B'B of instrument B. Theinstrument circuits are normally open at each subscribers station at thecontacts A B which are controlled by the receiver hook and are closedwhen thelatter is released by the subscriber removing his receivertherefrom. Each pair of wires constituting the circuits ofthe telephoneinstruments is extended to the aforementioned switches located at thecentral oflice and terminate in immutable contacts located thereon,those of the wires AA being located on the switch F, as indicated by Athe corresponding contacts on the switch C being indicated by A -A saidcontacts being tied. together by conductors A -A the similar contacts ofthe wires BB- on the switch F are indicated by B"" and onthe switch C byB -B said pairs ofcontacts being also tied together by wires B Theoperating mechanisms controlling the movable elements or wipers of thetwo switches have been omitted from these illustrations but as willappear more fully hereinafter, they are designed to cause such switchesto move progressively over a bank of contacts or terminals, representinga large number of telephone lines. The wipers of the switch F areindicated by F-F and those of the switch C by C-C the correspondingwipers of thetwo switches being connected by 1 wires 4 and 5. From aninspection of Fig. 1 it will be seen that the complete circuit betweenthe instruments A and B is traced as follows:- instrument A wire A,contact A ,;wiper F, wire 5, wiper C contactgB", wlre B, instrument B,wire B contact B wiper C, wire 4, wiper F, contact A, wire A, instrumentA. The foregoing, is predicated upon the fact that the call originatedat the instrument A and the mechanism of the finder switch operated topick u the contacts of the incoming cirthe switch C. These elementsarearranged one below the other and their outer endsare ment B.

Supposing a reverse operation to be ef-,

The movable ,ele

fected in a like manner. ments of the finder switch F first traversesits bank ofcontacts or terminals, until reachthe terminals -B then. theconnector switch C operates to pick up the terminals A -15. of-

The circuit between the the line AA two telephone instruments will thenbe traced as follows: instru'mentB, wires B B contact B wiper F, wire 4,wiper C, contact A, wires A, A instrument A, wiresA, A", contact A,wiper C, wire 5, wiper F3, contact B,'wires B", B, instru- T heswitches.

In illustrating the mechanism by means of which the connections betweenthe lines is efl'ected,'a type of switch adapted for this urpose isshown in Fig. 3, details thereof eing shown in Figs. 4 and 5.Thisfswitch is capable of performing the functions of either the finderor connector switch, and comprises generally a progressively movablemember 6, which is adapted to be advanced step-by step, and to thisendis made circular in form and is mounted upon a revoluble shaft 7journaled at its lower'end in the base plate 8, and supported at itsupper'end by a bearing on a bracket 9, the" ends of which extenddownwardly and are secured to the base plate, as shown in Fig. 5.Carried on the movable member and insulated therefrom are contact,elements or spring wipers 10 and' 11, corresponding to the wipers F'-Fof the switch F and C'-C of adapted to coiipe'rate with a series ofinsulated terminal contacts 12 and 13, arranged in pairs correspondingto the contacts.

A etc., those of each pair being lo cated in vertical alinement as shownin Flg.

4. As each switch controls a plurality of telephone lines, these pairsof terminals are supported upon a segmental bridge 14, and are arrangedconcentric with the center of movement of the wipers. Beneath saidcontacts are other contacts 15 and 16 with which of the line.

the shaft 7 a coil spring 20 to which suflicient tension is applied toreturn the shaft and the parts supported thereon to the normal position,shown in Fig. 3, when they are released. 1

The 'means for operating the movable element comprises a pawl 21',pivoted to the upper end of an arm 22 on which it is moved by a. spring23 into engagement with teeth 24 on the periphery of the element 6. Thearm 22 is pivoted at the point 25 and is provided with a laterallyextending end 26, forming an armature which coiiperates with the-motormagnet 27, employed for actuating the, operating devices, said armaturebe-- ingnormally held in retracted position by the spring 28 bearingagainst the stud 29 on the arm 22, which also serves to advance" themember 6 when the pawl 21 is in engagement therewith. A spring operatedpawl 30 serves to lock the movable element in adjusted position and atits outer end is a fin-' ger 31, projecting beneath ,theend of the pawl21, the arrangement of the parts being such that when the pawl is moveddown-' wardly into an inoperative position the .detent will beretracted, as shown in Fig. 3. The means for effecting the release ofthe member 6 comprises'a spring latch member 33 having an end 34 whichis adapted to hook over the edge of a lip 32 depending from the pawl 21.At its lower end the spring, 33 is attached to an armature 35 pivotallysupported in proximity to the release magnet 36 and carrying an upwardlyextending arm 37 provided with a stud 38 with which cotiperates a spring39 normally tending to move it in a direction to retract the armature'35. Supported uponthe base plate 8 in front of the spring 33, is a stud40, whlch llmlts the lateral movement of the springwhen the armature 35is retracted,

thereby permitting the lip 32, of the pawl to be disengaged from thehooked end of the spring when said pawl has been re-, tracted by theenergizing of the motor magnet 27 The movable member, 6, controls twocircuits, as will be further described in connection" with thediagrammatic illustrations, which include a contact spring 41 playingbetween contact members 42 and 43, supported in a holder 44, on the baseplate 8. The spring 41 has a normal tendency to engage the contact 42,but is heldin engagement with the contact 43, when the member 6 and thecontact elements carried thereon are in their normal position, by-a pin45 mounted on the member, which releases said spring upon the first stepor movement imparted thereto.

The finder and connector switches are actuated by electromagneticdevices peculiar to each, those ofthe finder switch being antomaticallyset into operation, and controlled by secondary circuits, which areestablished when an instrument circuit is closed at the subscribersstation, and the mechanism of the connector switch is rendered operativewhen the finder switch has picked up the incoming or calling circuit andis controlled by impulses of current which may be despatched by asuitable form of impulse transmitter located at the subscribers station,to select a given outgoing line, or called circuit. Accordinglytheinstrument circuit, comprising wires AA is extended, as indicated at AFigs. 1, 2 and 6, to normally closed contacts AA, one of which ismounted upon a spring finger provided with an end 46 adapted tocooperate with teeth of an impulse transmitter A which may be rotated toseparate said contacts and thereby transmit or send over the operatingcircuit one or more impulses of current, when the circuit is closed atthe hook contacts A The electromagnetic mechanisms for causing thevarious switches to perform their respective functions, are all adaptedto be operated from a common battery Z, Figs. 7 and 8, but in order tofacilitate the description and illustration, and render a morecomprehensive understanding of the variouscircuits to be had, these areshown in the diagrammatic views as receiving current from diiferentsources or sets of batteries,

ZZ etc. The circuits in many instances, are shown with the conventionalground or earth connections, but it will be understood that where theterm ground is employed and shown, it refers to a connection leadingdirectly to one side of the main battery, so that a telephone systemembodying this invention, when installed in working order, is entirelyfree of the so called grounds employed for actuating parts of theapparatus, thereby eliminating line disturbances or other troublesattributable to this cause.

The finder switch.

Associated with each telephone line or instrument circuit, is anactuating relay A, which is energized when the instrument circuit isclosed to actuate the operating mechanism of the finder switch F, and acut-oflf relay A, the function of which is to restore the actuatingrelay to normal position when the finder switch has picked up itscorresponding instrument circuit. In Fig. 6 the finder switch is shownprovided with a plurality of sets of the four terminal contacts whichare arranged in rows, as illustrated in Fig. 4, those constituting thelower pair of the set related to the circuit of instrument A. beingindicated by ff Leading from the contact f is'a wire A connected to oneend of the'coil of the cut-off relay A, the other terminal thereof beingsupplied at certain times with current from the battery Z; another wireA leads from the contact "f2 -to a back contact a, with which the ed bya wire a which is joined to the other wire A" of the instrument circuit,This armature normally engages a backcontact a which; has a groundedconnection; .2 In Fig. 7 corresponding parts to those just describedarefound illustrated in connection with the instrument B, said partsbeing indicated by the use of the letters B, b, with the appropriateexponents, reference to which will be made hereafter in explaining theoperation of certain parts of the apparatus.

It has been explained, in connection with Figs. 3, i and 5, how themovable contact elements cooperate with the several terminals in thebank of contacts of each switch, but in Figs. 6 and 7 the illustrationsare simplified by showing the circuit wires connected directly to thewipers, whereas, in reality they are connected to brushes, such as 10",11, 17 18', shown in Fig. 5. Referring now particularly to Fig. 6, itwill be seen that the brushes FF are extended by the wires 4* and 5through normally closed contacts on the armatures of two relays F Fwhich will be described more fully hereinafter, the function ascribed tothe former being that of opening the extended instrument circuit overthe Wires 4 and 5, during the rotation of the brushes of the finderswitch F, when moving in one direction to pick up an incoming line,while that ofthe latter relay is to open said circuit during themovement of these parts when returning in the opposite direction totheir normal position. The opening of the ties between the switcheseliminates any vibration in the receiver of a subscribers telephone whena plurality of switches are employed for the purpose of handling two ormore incoming calls simultaneously, and it also prevents any possibleinterference with the connector switch mechanism during the retrogrademovement of the parts of the finder switch.

Operating conjointly with the motor and release magnets, 27 and 36respectively, is a relay F which performs dual functions, namely: thecompleting of a secondary circuit of the motor magnet 27, over whichcurrent is supplied to cause its continuous operation until the wipersof the switch F have picked up the incoming line, and to close anothercircuit by means of which the cut-off relay A of said line is energizedwhen its terminals have been found by the finder switch. The motormagnet 27*, the relay F and the line opening relay F are connected inparallel by the wires f-f but as the relay F will he referred to morefully hereinafter, it may be disregarded at this point and the wire fconsidered as grounded or connected to one terminal of the battery Zwhich supplies current to the starting circuit controlled by thearmature a of the actuating relay A, Connected to one end of the coil ofthe motor magnet 27* is the batteryZ, the other end of said coil beinconnected by the wire f to the armature f of themotor magnet, whichnormally enfined to the gages the back contact f of the wire f. Thelatter is also joined to the contact 7? with which the spring controlledswitch arm f normally engages, the latter being connected by the wire fto the front contact f which is engaged by the ar'matureaa when thelatter is attracted by the actuating relay A The other contact'withwhich the switch arm f cooperates, is indicated by 7 3, and this has aground connection, 2 over which current is transmitted at certain timesto permit the finder switch to be restored. The

third wiper, f" is connected by the wire 8 to an armature f on the relayF normalfy resting against a back contact f which is connected by thewire f, to a round a), over which current may be received from thebattery Zto energize the cut-off relay A, when the brush f" engages thecontact f. The fourth brush f is connected by the wire f" to an armaturef, adapted to normally cooperate with a back contact f connected .by awire f to ground. This armature, i is also arranged on the relay F andwhen the latter is energized 1t 1s moved into engagement with thecontact f connected by the wire f= to the wire f.

The foregoing description has been conarts of a single telephone circuitbut itwlll be understood that the finder switch F serves a comparativelylarge number of such circuits, each of which has associated with it thepreviously described actuating and cut-01f relays. The l1ne wires A, Aand the local wires A and A of the several telephone circuits, areconnected to the respective terminals of each her in the bank ofcontacts (such as those indicated by 12, 13, 15 and 16 i1; Fig. '4.)

All of the instrument circuits when not in use, are normally open at therecelver hook contacts A, and as the brushes of the finder switch, undersuch condition, are 1n inoperative condition, the spring sw tch f 1sretained in engagement with lts back contact I". In order to facilitatean understandmg of the movement of the finder switch, an addit onaltelephone instrument has been: illustrated in Fig. 6; which is indicatedby D. This subscribers set comprises the actuat 1ng relay Doperating'the armature d, which is grounded at a and cotiperates withthe back contact d connected by the local wire D to the terminal (1 onthe SWIFCh F. The cut-off relay of this set is indlcated by- D, thecircuit of which includes the wire D leading to the contact (Z on theswitch F.. In the illustrations the terminals (Z and al of theinstrument set D are purposely located in front of the terminals f and fwith reference to the direction of rotation of the wipers of the finderswitch, in order to facilitate the description of the circuits which aresuccessively established by the movement of the switch.

Automatic operation of the finder switch.

When the subscriber at station A removes his receiver and closes thehook contacts'A the following circuitis established: instrument A, wiresA a armature a, contact a wire a, relay A, battery 2'', by ground to Zcontact a", armature a, wires a and A back to A. The energizing of theactuating relay attracts the armature, afl'completing the followingcircuit: ground a armature a contact f, wire 7', spring f, contact f,wire f, contact f, armature f wire f motor magnet 27*, battery Z toound. The foregoing is termed the startmg circuit and that partextending from the con tact f is common to every instrument cir- Y cuitleading to the finder switch and coiip 'erates with the several branchesconnected to the spring f anyone of which may be closed by itsrespective actuating relay, to primarily actuate the motor magnet, whenthe switching of current causes the movable member of the switch to beadvanced one step,,permitting the spring switch f to disengage thecontact f and the four wipers to engage the first tier of contacts of anincomlng line, for instance those of the line D, but as the relay F wasalso energized, the armatures f and f thereon were attracted, the lattercompleting the following circuit: battery Z, magnet 27, wire f armaturef contact f wires f, f" contact f, armature spective instrumentcircuits.

wire 7 brush f contact al wire D contact (i 9 armature cl, to ground .2

It should be stated at this point that the core of the relay F 5 isprovided with a copper jacket, or otherwise constructed, to render itsoperation sluggish, so that the armatures f and f are'not released themoment the armature f is attracted by the motor magnet 27%. For thisreason it will be seen that the dlflerence in the time constants of thismagnet and its associate relay permitsthe switch brushes-traverse thebank of con tacts, and step from one set of terminals to another. Asboth of these circuits are completed through the brush or wiper f theyare common to all of the instrument circuits connected to the finderswitch and the local wires such as A, D, constitute branches of saidcircuits which are controlled by the actuating relays of the re- All ofthe o crating circuit branches are normally closed or connected to oneside of the battery when the actuating relays are denergized; while thestarting circuit branches are all opened. Consequently the energizing ofa line relay reverses the condition of the branches. under its control,namely, it closes the starting circuit and opens the operating circuit.It will therefore be seen that each time the wiper f passes onto acontact, grounded as at a, an additional impulse of current is given tothe motor magnet of the switch and the onward movement of its wiperswill continue until the wiper 7 reaches a terminal of the operatingholding circuit branch belonging to the incoming line on which the callwas originated as said circuit branch will then be open at the actuatingrelay armature. This is shown in Fig. 6 in which the armature a is heldout of engagement with the contact a by the actuating relay A which wasenergized when the circuit of instrument. A, the calling line, wasclosed.

The cessation in the flowof current in the circuits in the motor magnet,27 and the relay F permits the armatures on the latter to restore ordrop back to their normal position thus permanently breaking theoperating circuit at the contact f At this time the brush or contactelement f" is in engagement with the terminal 1' and the followingcircuit is established:

Battery Z, cut ofi' relay A, wire A contact f brush f wire f armature fconrelay A. As the Wipers FF are at this time in engagement with thecontacts A A, respectively, the telephone circuit is then extendedonward to the connector switch. J

Restoring the finder "switch to normal. The restoring of the finderswitch F occurs when the instrument circuit which is closed in the firstinstance to actuate it, is

subsequently opened, as occurs when the calling subscriber hangs up hisreceiver and opens the hook contacts A The releasing magnet 36 isarranged in acircuit which includes the corresponding magnet of theconnector switch C, which may be traced on Figs. 6 and 7 of thedrawings. In order to simplify the description at this point, atemporary circuit has been indicated in Fig. 6 by the dot and dash line,although the full release operation cannot be stated except inconnection with the connector switch C, as there are contacts in thetruecircuit of the release magnet 36*" which are opened when thetelephone instrument circuit is extended by the finder switch. Thebattery supplying current to the release magnet 36 is indicated by Z andbetween it and said magnet is a current interrupter Ff, which in thepresent illustration is shown as a rotary element adapted to be drivencontinuously by any suitable source 'by a circuit wire, f, as shown bythe dot and dash lines, joined to the armature f arranged on thecontrolling relay F which attracts the armature away from its backcontact, f connected by a wire f with the spring switch arm f. As'beforemen tioned, the contact 7' is connected to the ground 2", which formsthe other terminal of'the battery Z It will be remembered that, duringthe rotation of the movable elements of the switch F, the controllingrelay F is energized, consequently the circuit of the release magnet isbroken by the armature f despite the fact that the other opening in saidcircuit is closed by the spring switch arm f, upon the first movement ofthe switching mechanism. The circuit of ground 2 the release magnet 36,may be traced as follows; when the switching mechanism ceases operation:battery Z brush i current interrupter F brush f, wire f, magnet 36* wiref, armature f contact f wire f", spring switch f, cont-act f, to Theenergizing of therelease magnet causes the movement of its armature andthe retraction of the detent and pawl (parts 30 and 21, shown in Fig.3), permitting the movable element to be returned to its normal positionby the coil spring 20 (shown in Figs. 4 and 5.) 'The last describedcircuit is opened at the connector switch C before the slow operatingrelay F releases its several armatures, as

will be more fully described hereinafter, so,

that the temporary circuit wire f may be disregarded. I

The connector switch.

The connector switch comprises appara-' C'-C to permit theiradjustmentinto engagement with the terminal contacts of any instrument circuit onsaid switch and fur-- ther, to render the circuit so connected (theoutgoing called line)'engaged or busy to prevent the called subscriberfrom attemptmg to set up a different connection through ThlS theswitches F and C, at this time. mechanism is illustrated in detail inFig. 7, and it is also shown upon a larger scale in F i 8. ssociatedwith the connector switch is the signaling and answering mechanism, theoperation of which is effected by virtue of the aforementionedcontrolling devices, but as the circuits which are established forperforming the functions of signaling and answering are not completeduntil after the controlling devices have performed their operations,this mechanism 15 illustrated separately in Fig.- 10.

Among those persons versed in this art it is customary to designate thetwo conductors of a telephone circuit, (such as A, A,) as the line andmate wires, and as these expressions will serve to elucidate furtherdescription, this nomenclature will be adopted. I

In tracing the circuit from the switch F to the switch C, it will beseen that the line and'mate wires P and 5, leading from the brushes,F'-F (in Fig. 6) are extended as indicated by P -5 (in Fig. 7)

V to the wipers CC of the switch C, and

have interposed therein condensers 47 and 48 and are supplied withcurrent from the battery-Z by wires 49 and 50 leading to the line andmate respectively. Inter-posed in the battery wires, 49 and 50 are linebalancing coils 4 5 the latter being also used as a relay for performingone of the steps in establishing the signaling circuit. The line andmate conductors, 4 5, form the tie between the finder and connectorswitches and leading from these conductors are branches 40 and 50, whichare com nected, respectively, .to one end of the coil of the line relay41 and the coil of the mate relay 51 The other end of the coil of thefirst mentioned. relay is connected by the wire 4" to a battery Z andthe corresponding extremity of the other coil is connected by a wire 5to a ground 2, corresponding to said battery, whereby, a current impulsetherefrom will cause both the line and mate relays to be energized whenthe brushes FF of the finder switch F are in cooperative engagement withthe terminals of theincoming lines These two relays are associated withthe motor magnet 27 and the release magnet 36, of the C switch, andtogether they-control these magnets in the performance of theirrespectix e functions. These relays also have a time relationship, themate. relay being preferably the one which .is so constructed as to havea more sluggishor retarded action than the line scribers station, and todestroy said circuit.

to prevent the operation of the motor magnet and render it inoperativeto other current impulses subsequently transmitted over said circuit.The line relay 41 controls an armature 0 connected to one end of thecoil of the motor magnet 27 by thewire c and cooperating with a backcontact, 0 connected by the wire 0 with an armature '0, 9n the materelay 51*, which attracts it into engagement with a forward contact 0"connected to the battery Z by the wire a. The other end of the motormagnet coil is attached to the wire 0 which has a ground loo . relay, sothat its armatures will be held in attracted position during thevibration ofa over which current impulses from the battery Z arereceived. It will be seen therefore that current in the line and matewires simultaneously energizes the two relays, the line relay openingthe circuit of the motor magnet by attracting the arma-' mm 0 at theinstant the mate relay attracts the armature 0 preventing the energizingof the motor magnet until the armature 0 is released.

The complete circuit of the line and mate relays can be traced asfollows: Fig. 7, battery Z, wire 4* line relay 41*, wires 40 4*, Fig. 6,wire 4, brush F contact A, wire A instrument A, wire A, contact A, brushF Wires 5, 5, (Fig. 7) 50 mate rel'ay 51, wire 5, to ground a. Theoperator at subscribers station A now despatches the de sired number ofimpulses over the aforedescribed circuit, to actuate the connectorswitch, and cause itswipers, CC to move into engagement with theterminal contacts of the outgoing line circuit, on which he desires tocall a certain party, by opening and closing the circuit delineatedabove, the requisite number of times with sufficient rapidity to releasethe armature c and to continue its vibration to successively close andopen the circuit of the motor magnet 27.

To illustrate this selective operation succinctly, let it be consideredthat the called subscribers station, heretofore referred to as B, is theinstrument of which the line and mate wires are connected with the setof contacts designated by the numeral 400 in Fig. 3, which is thefortieth set of contacts in the bank of contacts of the connectorswitch, necessitating forty steps of the movable contact elements orbrushes before the latter can engage them. The impulse transmitter, Awill, therefore, be operated to open and close the contacts A and A,forty times; each impulse of current over the incoming line and matewires (A' A 5 will energize both the line and mate relays, ell--59, butas the latter has a slow or retarded action, it does not release thearmature c, and the latter is, therefore, held in engagement with thecontact of during the vibration of the armature c which is attracted andreleased each time the incoming circuit is closed and opened. Consequently a series of impulses in unison with' those transmitted over theincoming circuit b the successive opening and closing of t e contacts Aand A, at station A, are transmitted over the motor magnet circuit,which may be traced as vfollows: battery Z, wire 0, contact 0, armature0", wire 0 contact 0 armature 0, wire a, magnet 27 wire 0", to ground ZUpon the cessation of these impulses the brushes oi the connector switchstand in the posit1on sho wn in dotted lines in Fig. 3. In considering Fig. 7 further, the brushes C'C will be contact 0 to ground, 2

borne in mind as engaging the contacts B and .B.

Rendering a called line engaged or busy.

which leads the wire 0 terminating in an armature a arrangedon the localrelay C,

and cooperating with a back contact, 0

connected to a ground a over which current impulses are received fromthe battery Z connected with the coil of the cut-off relay B, andsupplying current to the following circuit: battery Z relay B, wire Bcontact 0, brush 0, wire 0 armature c, The foregoing circuit energizesthe cut-off relay of the outgoing called line to prevent the calledsubscriber from disturbing the finder switch when he answers the calland closes his line through the hook contacts B The complete talkingcircuit from instrument A, the calling line, to instrument B, the calledline, may now be traced as "follows: Fig. 7,

condenser 47, wire 4', (Fig. 6) wire 4, brush F, contact A, wire A,instrument A, contact A, brush F wire 5, (Fig. 7) wire 5', condensen 48,brush C contact B wire B, instrument B; wire B contact B brush C, wire4. Current is supplied for part of the talking circuitfrom the batteryto the two conductors 4 and 5 by the wires 49 and 50 and the other'partof the circuit is supplied with current from battery Z. V v

Delineated on Fig. 7 arethe bond wires connecting the correspondingterminals of the lines of instruments A, B, and D, on the switches F andC, which arrangement allows a call to be initiated on any line andperinits one to be received from an other line. These bonds leading toswitch are designated as follows: A leading from the wire A to thecontact A A leadin from the Wire A to the contact A; an the wire A,leading from the wire A", to the contact A In order to prevent theoperation of the cut-off relays of those lines of the connector switchwhose terminals are traversed by the brush 0", the circuit of said rushis opened during the rotary movement of the connector switch and it isto this end that the.

armature c is arranged on the local rela C. connected by the wire a,with the back contact 0", with which the spring switch a Aywire One endof the coil of this relay is i the movable member of the switch C, whenthe latter is in its normal position. The other end of said coil isextended by the wire'o to an armature a, on' the mate relay 51, whichcooperates with a forward contact a, connected bythe wire 0 to the wirea, leading to the battery Z". The spring 0 is connected bv the wire 0 toa ground, Z" receiving impulses of current from the battery Z", fromwhich it follows that," when the mate relay, 51 is energized, thefollowing circuit is established: battery Z, wires 0 and 0", contact 0armature 0, wire a, relay C wire o contact a, spring switch a, wire 0 toground 2.", thus energizing the local relay C and opening the circuit ofthe brush 0", at the armature 0. A holdingcircuit is established forretaining current 1n the local relayv G, during the operation of themotor magnet 27, by connecting to the wire o an armature 0 which isattracted into engagement with the terminal 0 of the wire 0 whichterminates in a back contact 0 of an armature 0 (on the line relay 41connected by a wire a, with aground 2 also adapted to receive currentimpulses from the bat tery Z. This holding circuit may be traced asfollows: battery Z, wires 0, 0 contact 0, armature 0, wire 0", relay Cwire 0 armature 0, contact 0 jwire 0 contact 0, armature a, wire '0, toground 2". Now, as both the relays C and 51 are so constructed as todischarge their residual magnetism slower than the line relay 41 does,the armatures 0 and e are held in attracted position during thevibration of the armature c and each movement of which supplies thecurrent necessary to keep up the magnetism in the relay C until thepulsations of current over the line and mate conductors cease.

Upon the cessation of impulses from the impulse transmitter, A, thecontacts A,

A thereof, are in engagement thus, leaving the telephone circuit closedand causing a break in the regularity of the transmission of saidimpulses, so that the line relay is energized holding the armatures cand a in attracted position. This interruption arrests the motor magnet27 and allows the magnetism in the core of the relay C to seep or leakout, to close the circuit of the 55 cut-ofl' relay B, of the selectedoutgoing line.

Restoring the connector switch to normal.

lhisis-acc omplished by extending the circuit of each of'said magnetsthrough an armature 136 which is attracted when the mate relay 51 isenergized. This armature normally rests against the back contact Q,connected by a wire 0 with one end of the coil of the release magnet 36and similarly connected by a wire a with one end of the coil of therelease magnet 36 of the switch F. The other terminal-of the coil 36 isconnected by a wire a, with a brush a, of a current interrupter, G withwhich cooperates the brush a, leading to the battery Z. The currentinterrupting devices of the switches F and C, are, in practice, one andthe same, and the batteries Z and Z represent the source of currentsupply from a main battery-all as shown in Fig. 8. The armature 136 isconnected by the wire o with the forward contact a, of the pair ofcontacts cooperating with the spring switch arm 0. This armature is alsoconnected by the wire 0 to the armature f, shown in Fig. 6, on the relayF. When the connector switch has been actuated out of its normalposition, the spring switch arm 0 engages the back contact, 0 and whenthe circuit over the line and mateconductors is broken, by the openingof the contacts at the subscribers station, such as A the armature 136is released and engages the back contact a, completing the followingcircuit: (switch C Fig. 7 battery Z brush a, current interrupter C brush0 wire 0 release relay 36, 'wire 0, contact 0, armature 136, wire 0contact a, spring switch a, wire o flto ground a", over which theimpulse or impulses, of current are sent to permit'the movable elementof the switch C to return to its normal position. At this same instantthe following circuit has also been completed: (switch F. Fig. 6)battery Z brush f, current interrupter F brush f, wire f, mag net 36wire 0 (Fig. 7 contact 0, armature 136, Wires 0 0", (Fig. 6,) armature7', contact f wire f spring arm f, contact f, to ground, .2 When the twoswitches, F. and C, are idle the armatures f? and 136 are each inengagement with their back contacts so that if the movable elements ofeither, or both, of the switches F and C are adjusted out of theirnormal position by manual manipulation, they will be returned by currentoperating the separate releasing magnets over the aforedescribedcircuits. it will also be seen that if for any reason the finder switchF fails to pick up the line on which a call was originated, the movableeleinent will make a complete excursion over all until the incoming linehas been picked up. It will be understood that this repeating movementresults only when an unnatural condition exists, such as a delayoccurring in the operation of one or. another of the relays,particularly the cut-oil relay of the calling line, which, might occurif the third brush, i of the finder switch, should fail to establish acircuit with the respective contact f, the first time it is stepped intoengagement therewith. Likewise, if for any reason a subscriber shouldopen the line by hanging up his receiver immediately after it had beenremoved from the hook, the finder switch would automatically return toits normal position in readiness to be again started upon an impulse ofcurrent received over the starting circuit branch of any of the incominglines.

. Opening name. In exchanges serving a large number of telephoneinstrument circuits, the finder and connector switches are duplicated asmany times as need be, and on each switch appear the terminals of theline and mate conductors, which may be extended as shown in dotted linesin Fig. 7, provisions not referred to herein, being made whereby, two ormore connections may be set up at the same time. With such anarrangement of switches, it will be seen that where two line circuitsare connected over one set of switches, the movable contact elements ofanother set of switches in traversing their coming line and also for themoment of time when both switches are released, and are returning tonormal position. This is accomplished in the present instance by meansof the two relays F, and F, each controlling a pair of armatures, one ofeach of said pair being located in the circuit of the line and mateconductors respectively. The relay F, has been described as being in thecircuit of the wire f by means of which it receives current from thebattery Z and is energized during the operation of the motor magnet 27*.The relay F is another one of the so-called slow or retarded relays,oneterminal of its coil being connected by the wire f to the wire f, theother end of the coil being connected by the Wire f, to the wire 0whereby said relay is energized simultaneously with the release magnet36 whenever the circuit of the latter is closed by current impulsestransmitted from the current interrupter, F The armatures in the lineconductor 4.- are indicated by 42 and 43, the former being connected tothe wire 4 and coiiperating with the back contact, 44", joined by thewire 45* to the armature 43*, which normally engages the back contact46, forming the terminal of the wire 4*. The armatures of the mateconductor 5 are indicated by 52 and 53, which are connected by a wire5%, the former armature engaging a back contact or terminal 55 of thewire 5, and the. latter cooperating with the back contact or terminal56*, of the wire 5*. When the two relays F and F are deenergized theirarmatures are in the normal position (shown in Fig. 6) and this part ofthe talking circuit is traceable as follows: line conductor 4, armature42 contact 44", wire 45 armature 43 contact 46*, wire 4*; mate conductor5, contact 55 armature 52,

wire 54, armature 53 contact 56 Wire 5.

Ringing and answering circuit.

The description thus far has been confined to the operation of thevarious elements which occur in the setting up of the connectionsbetween two telephone lines and to the mechanism operating conjointlytherewith by means of which a connection is automatically broken and theswitches restored to their normal position. There still remains forfurther consideration additional mechanism by means of which thesignaling devices on the outgoing or called lines are operated, afterthe connection has been established, which are illustrated particularlyin Fig. 9.

Each telephone instrument is provided with signaling devices, such asthe usual ringer, (indicated by B, at station B, Fig. 9) which areenergized by signaling current from the generator C, supplied to the outgoing line circuit, such as the wires BB In order to supply this currentintermittently to ring the bells, or operate the signaling devicesperiodically, as well as to afford the. answering subscriber anopportunity to cut his instrument into the line, a signaling relay C isemployed. This relay is rendered operative by the conjoint operation ofthe line relay 41 and the local relay C the latter acting to temporarilyrender the signaling relay inoperative and open the conductors betweenthe source of signaling current and the movable contact elements, duringthe rotation of the brushes of the connector switch, so that thesignaling devices of other circuits are not operated as the brushes ofthis switch traverse their terminals in seeking those of the selectedline.

Dne end of the coil of the signaling relay C is connected by the wire 0to an armaswitch picks up the outgoin ture a, which is attracted, whenthe balancing coil 5 is energized, into engagement with the forwardcontact a, of the wire 0 leading to the battery Z. The armature a whenin normal position cooperates with a back contact a, connected, by .awire a", to a brush 0 of the current interru ter C", the second brush a,of which is connected with the battery Z. The other extremity of thecoil of the relay 1 is connected by a wire 0 to an armature 0 which isheld in attracted position with aforward contact 0 when the line relay415 is energized. The contact 0 is joined by the wire 0 to a backcontact 0, of an armature c on the local relay C, said armature beingconnected to a ground 2 which completes the circuit from the roundedsides of the batteries Z and Z nstead of extending the line and mateconductors 4 and 5* directly to the brushes C and C (as shown in Fig. 7)they are terminated in contacts 47 and 57 with which cooperate armatures48 and 58 on the signaling relay C said armatures being connectedrespectively with brushes C and C by Wires 49* and 59 The brushes 0* andc of the current generator C are con nected respectively by wires 0" and0 to aback contact a, of the armature 58, and an armature a, on the materelay 51". The armature a", when in attracted position, engages acontact 0 connected, by a wire a, to a back contact 0 of the armature48. It will be remembered that the line and mate relays 41 and 51*, areenergized during all of the operations occurring on the connectorswitch, consequently when a line circuit is extended, to the latter,from the finder switch, the armatures c 'and c are attracted and held inengagement with their respective contacts and that when said called linethe local relay C is deenerg zed, permitting thearmature to drop intoengagement with its back contact, 0. The following circuit is thenestablished: battery Z brush a, current interrupter C", brush a, wire 0contact 0 armature 0, wire 0",.signaling relay C wire 0*; armature 0",contact 0", wire 0 contact a, armature a, to ground, 2

The last mentioned current interrupter C, is in practice, the same as Cand F, and it serves to intermittently energize the signaling relay,which then attracts the armatures 48* and 58, in the line and mateconductors, in momentary engagement with the contacts 47 and 57". Now ifit should happen that during the moment of time in which these armaturesare attracted the subscriber should close his line at the receiver hookcontacts B the following circuit will be established from instrument Bto battery Z: battery Z, coil 4:, wires 49, a", contact 41 armature 48*,wire 49, armature 60, contact 61", wire 49, brush C, contact B wire Bcontacts 13 instrument B,

in the signaling relay C, which latter holds the aforedescribed linecircuit closed until one or'both of the subscribers open the connectedcircuit between their two instruments.

In order to prevent the signaling current from being despatched over theoutgoing instrument circuits successively, as the movable contactelements are advanced progressively, the parts 49 and 59 of the line andmate conductors are each provided with an opening adapted to be normallyclosed by arnlaturcs 60-T0 cooperating with contacts 6l -7l=h Thesearmatures a re arranged on the local relay C and are attracted by itduring the time the connector switch mechanism is selecting the givenline circuit.

The arlnatures l8 and 58 normally stand in engagement with their backcontacts and therefore the instant the wipers CC pick up the selectedline and the local relay C releases the armatures G0--70, the ringingcurrent is despatched from the generator C to operate the signalingdevices I5 overthe following circuit, (shown in Fig. 9): currentgenerator C brush 0, wire 0 armature 0, contact a, wire 0 contact 0,armatures 48*, 60, contact 61, wire 49, brush C, contact B wire B ringerB wire 13, contact B brush C wire 59, contact 71', armatures 58, contact0, Wire 0, brush 0, generator C Multiple smite/Les.

The length of time required to set up a connection, or establish a call,may be greatly shortened or minimized by emplo v ing a multiplearrangement of tinder switches, preferably arranged in pairs, theequivalent sets of terminals on each being arranged relativelv inreverse position inthe banks of contacts on the two switches, which inpractice gives the same result as would'be obtained if the mechanism ofone switch of a pair was designed to drive its contact elements in areverse direction relatively to the movement of the wipers of the otherswitch. The switch illustrated in Fig. 3 is provided with fifty sets ofline circuit terminals, requiring fifty movements or steps-0t the wipersto bring them into ongagement with the last set of terminals. and.although the switch mechanism travels with considerable alacrity, itwill be seen that the time required to enable the switch wipers to moreinto engagement with the last set of terminals, is twice as long as thatconsumed while the wipers are moving to the center of the bank ofcontacts to engage the twenty-fifth set of terminals. Consequently bytying each line circuit to two switches and either arranging theterminals thereon in inverse order or rotating the wipers of one of themin a relatively opposite direction to those of the other switch thetotal number of lines may be traversed in twentyfive steps therebyreducing the time to one half of that required by a single switch formaking the selection of a line having the highest number.

To describe this idea more specifically: The circuit of instrument B wasstated to be connected to the tortieth set of contacts, designated byL00 in Fig. 3, requiring forty steps of the finder switch F. On a secondfinder switch (such as F Fig. 10), the circult of instrument B would bejoined to the tenth set of terminals, occupying the position designatedby 100 in Fig. 3, so that the movable'contact elements of this secondswitch would only be required to move ten steps to select saidinstrument circuit. In Fig. 10 this duplication of finder switches isillustrated diagrammatically to show the arrangementof terminalscorresponding to the circuits of instruments A and D,,-0f b'igs. 6 and7. The switches]? and C are identical with those sliown in said figures,and the o 'ierating' mechanism-of the other finder switch F is like thatof the switch F, but associated with it is a separate connector switch Gwhich performs the same function as the corresponding switch 0, when aninstrument circuit is selected by the finder switch F. It will benoticedthat the sets of terminal contacts A"D" on the latter, are in reverseposition in the switch bank, relatively to the corresponding sets A 7 onthe switch F, while the sets of connector switch terminals D*D and it -Aoccupy the same relative position in the two switch banks.

The finder switch F is adapted to be actuated simultaneously with theswitch F and to this end its sprin contact arm f is also connectedto-all o the starting circuit branches by the wire i which causes bothswitches to start out to find a calling line circuit. The switch, themovable elements of which first pick up the terminals of said callingline circuit, will be arrested, as heretofore described, while the otherfinder switch continues its excursion. It will be rccollected that theinstant the finder switch is arrested the cut-ofl relay of the callingline is energized, permitting the operating-holding circuit branch,(previously opened) to be closed. The closing of this circuit branchoccurs before the movable contact elements or wipers of the other finderswitch (which is still advancing) engage the second set ;oit terminalsof the connected calling circuit. Consequently this finder switch is notarrested at said set of terminals but is permitted to pass over theentire bank of contacts until disengaging the last set of terminals whenit is automatically returned to its normal position. If the finderswitch F happens to be the one which picks up the incoming callingcircuit then the latter is extended to the associate connector switch Cwhich is operated to select the desired outgoing called circuit, theother connector switch C remaining idle.

In addition to facilitating the quick selection of an incoming callingcircuit, as before mentioned, this duplication of the finder switchespossesses the advantage of making the selection of a circuit doublyassured, for should the movable contact elements of one switch happen tomiss a connection, due to corroded terminals, or a too rapid movement ofthe wipers, or some other unaccountable cause, then the other finderswitch will pick it up.

Sub-station lamps.

To assist a subscriber in the manipulation of his impulse transmitterand the selection of other subscribers numbers, from his directory, aswell as to inform him of the operativeness of his own instrumentcircuit, an incandescent lamp, such as A B -D, is located at a suitablepoint in proximity toeach instrument set. This lamp is arranged in thecircuit of either the line or mate conductors which receive currentwhenever the instrument circuit is closed. The location of the lamp inthe-instrument circuit is rendered possible by virtue of the arrangementof the switching mechanism which is controlled entirely by impulses ofcurrent transmitted over the two instrument circuit conductors and isnot dependent for its operation upon earth connections, or a third linewire, cooperating with one or both of the usual line and mateconductors.

I claim as my invention:

1. In a telephone system, the combination with a switching mechanismcomprising a plurality of terminals arranged in sets, separate contactelements cooperating with each of said sets, amotor magnet for operatingthem and a plurality of instrument circuits, of a motor magnet relay, astarting circuit for said magnet and relay and an operating circuitcontrolled by the relay, said circuit leading through one of theelements and comprising branches leading from one set of switchterminals and corresponding to each of the several instrument circuits,an actuating relay controlling each of said

